Existing manual tube cutters already disclose screw means for adjusting the tube cutter as a function of the diameter of a tube to be cut: see for instance Canadian patents 60,683 and 354,163. Moreover, adjustment of the tube cutter anvil rollers has been anticipated in the published Canadian patent application No. 2,003,542, and adjustment of the tube cutting knife itself, in U.S. Pat. No. 3,795,051. The latter patent, together with U.S. Pat. No. 2,739,381 further disclose means for relatively quick release of the knife from the tube cutter. Other relevant documents include the following U.S. Pat. Nos. 2,300,139; 2,824,772; 2,921,369; and 3,216,110.
In these known pipe cutting tools in which the cutting knife is releasable, the means to releasably secure the knife to the tool are usually of the screw type or the snap ring type. The screw type, illustrated in FIG. 6 of the Stein patent (U.S. Pat. No. 2,300,139), involves the knife axle itself being releasably screwed to the cutter frame. The snap ring type, embodied in one of the above-referenced Peterson patents (U.S. Pat. No. 2,739,381) involves installing a split snap ring, reference 18 in FIG. 2 of this latter patent, which will expand into locking engagement with a tangential groove about one end of the knife carrying axle.
Such known knife axle lock means for cutting tools are deemed by the inventor as being clumsy and not as efficient as one would like.